Houghton a/c youtube re: humidity issues

[SteveCr]

Hull 806....investigating replacement of the Dometic AC....Truma or Houghton?

My main and common motivation is the Dometic decibel issue.

In researching replacement experiences with the Houghton, I ran across the attached youtube testament.

At about 13:00, the couple discuss a new humidity issue. Here is the alarming quote.

"Well it's been about six weeks since we installed the Houghton air conditioner from RecPro and ultimately we've still been unable to get rid of this humidity issue. We've been in North Carolina, we've been in Florida - we're now in Illinois and the humidity levels in the camper are unreasonable to us".

They go on to state the humidity will decrease to the 50's during the day but increase to the 80's at night. I believe they attribute this to the constantly running fan with the compressor being off.

This is shocking to me because they seem to be seasoned campers and are comparing the humidity issue to their previous Dometic AC. They resorted to running a "house size" dehumidifier.

Still, they state in this and a follow up video that they would again install the Houghton due to the decibel improvement.

In the comments on their youtube video their are others that state they are seeing a similar humidity issue.

So......not sure what to make of this. Comments?

 

[Katjo]

WoW! Will be interesting to hear from Ollie owners who installed/have the Houghton. 

[SeaDawg]

Split this off to its own topic. 

For those of you who would like to read their comments,  here's a plain text link to this video on their channel, which may make it easier for you.

https://youtu.be/nrvLZilFvnQ

As someone who lives in a high humidity area (coastal Florida), I would definitely say that running the a/c  fan on high instead of auto is not recommended, in our homes,  @SteveCr. That, along with weak batteries in the remote, probably contributed to their issues. Let's see what their followup video shows. She didn't have a comparison with the old ac, as it was their first time camping in Florida ( i think that was in comments.)

We've not used our Houghton ac sleeping in our little camper overnight,  so I  can't comment on its performance with humidity that we generate cooking, breathing, and showering. 

 

[GarryandKristi]

On 10/3/2022 at 1:47 PM, SteveCr said:

Hull 806....investigating replacement of the Dometic AC....Truma or Houghton?

My main and common motivation is the Dometic decibel issue.

In researching replacement experiences with the Houghton, I ran across the attached youtube testament.

At about 13:00, the couple discuss a new humidity issue. Here is the alarming quote.

"Well it's been about six weeks since we installed the Houghton air conditioner from RecPro and ultimately we've still been unable to get rid of this humidity issue. We've been in North Carolina, we've been in Florida - we're now in Illinois and the humidity levels in the camper are unreasonable to us".

They go on to state the humidity will decrease to the 50's during the day but increase to the 80's at night. I believe they attribute this to the constantly running fan with the compressor being off.

This is shocking to me because they seem to be seasoned campers and are comparing the humidity issue to their previous Dometic AC. They resorted to running a "house size" dehumidifier.

Still, they state in this and a follow up video that they would again install the Houghton due to the decibel improvement.

In the comments on their youtube video their are others that state they are seeing a similar humidity issue.

So......not sure what to make of this. Comments?

 

Relative humidity is a pretty worthless measure of moisture in the air as it changes with ambient temperature (rh is the amount of moisture, or vapor pressure to the amount of moisture or vapor pressure at saturation) and warm air can hold more moisture than cold air.   I am a big fan of dewpoint (temperature at which moisture condenses in the air) which doesn’t change unless you get a different air mass. I suspect the issue is running the fan constantly versus on auto so unconditioned air is being pulled in.  We run our dometic on  low (not auto) so the startup of fan/compressor isn’t so alarming. I do notice an immediate change in humidity with our domestic when the compressor turns off (but fan  still runs). With a quiet AC it would be better to run it on auto so that the fan is not running when the compressor is off.  So I am thinking it is not so much to do with the manufacturer/unit as it is the mode of operation. 

[NCeagle]

We have the Houghton and I do find everything in this video to be accurate (I also have data to confirm this).  We do use a dehumidifier along with the Houghton to control humidity/dewpoint AND temperature.  I think this is normal as an AC unit is specifically made to operate based on temperature (not humidity) and a dehumidifier is made to operate based on humidity (not temperature).  I know lots of people in NC that have a dehumidifier in their home and run AC and the dehumidifier to control both humidity and temp.

Auto on the Houghton does not stop the fan from running when the compressor is off.  I thought it was just circulating the cabin air when the compressor is off, but if it' s mixing in outside air that may be something that could be improved with the design, but it still wouldn't control BOTH humidity and temperature.   

What I've found works best for us is keeping the temp set at the lowest point (60F) when cooling so the compressor doesn't shut off.  The cabin cools quickly and the dewpoint drops dramatically just as quickly.  Once we've got the temperature where we want it, we turn off the AC before it starts cycling.  The dehumidifier then keeps the dewpoint in check so even if the temperature goes up, it's still "comfortable".  If the temperature does get uncomfortable, it means waking up in the middle of the night and running the AC for about 30 minutes to get things comfortable again, but this is rare.  On nights when I know it's going to get too hot, I've used the timer function to have the AC come on for 30 minutes in the middle of the night and then shut off again without me having to manually turn it on and off.

 

[CRM]

I think a big part of the humidity issues some are having is that most units are oversized for the volume of airspace being conditioned, especially when that airspace is well insulated like our Ollie's are. In high humidity conditions temps are knocked down quickly (but the humidity is not) which results in short cycling of the unit. The humidity issue is made worse by setting the fan to the "on" position since once the compressor shuts down any moisture still on the evaporator coil will be sent directly back into the living space as vapor and will not have the time to drain to the outside as intended. We have an older Coleman 9.2k unit and have no such issues with humidity even though we do all of our camping here in Florida where it's almost always hot and humid. We usually set the thermostat to around 70 and the fan to "auto-low" which pretty much keeps the unit running non-stop and humidity at 50% or below. Not sure if these Houghton's have an "auto-low" setting, but I highly recommend using that setting in high humidity conditions.  Might also be a good idea to contact the manufacturer to see if the fan's CFM (cubic feet per minute)  is adjustable as it is in residential AC units. A lower fan speed would help remove more humidity by increasing the run time of the compressor.

 

[SeaDawg]

Interestingly enough, in the Houghton 3400 (13.5 btu) manual I found online, houghton suggest running the fan on high instead of low or auto in low humidity... 

Houghton is distributed by Finch in Australia.

We don't have auto low, but we do have a dehumidifier mode on our 9500, which I tried in the sideyard one day. It seemed to work, but I have no data to bCk it up other than seeing some condensate drip off the roof...

[CRM]

12 minutes ago, SeaDawg said:

Interestingly enough, in the Houghton 3400 (13.5 btu) manual I found online, houghton suggest running the fan on high instead of low or auto in high humidity... 

Houghton is distributed by Finch in Australia.

This actually talks about sweating in a low humidity environment, not high. 

[SeaDawg]

Oops. Thanks for the catch. See what I get for speed reading with too little caffeine...

I fixed my post. I think I now understand why the folks in the video might have run theirs on high... when it made no sense to me...

[CRM]

1 hour ago, SeaDawg said:

Oops. Thanks for the catch. See what I get for speed reading with too little caffeine...

I fixed my post. I think I now understand why the folks in the video might have run theirs on high... when it made no sense to me...

Their humidity problem is undoubtedly being caused by either the unit being oversized (my guess) or they aren't running it in dehumidifying mode or low speed fan setting (if that unit has such features) while operating in humid conditions.   

[SeaDawg]

@CRM, I agree. And, I think Ll the Houghton units have dehumidifier mode. (My understanding of that mode, from a friend in the marine industry,  is that it's usually a mild ac mode, with low fan setting.)

I'm quite sure the 9500 is enough for our smaller Elite. Especially since we rarely camp in high heat. The original 13500 dometic on our Elite would freeze us out in a hurry. Way overkill. 

[NCeagle]

14 hours ago, CRM said:

Their humidity problem is undoubtedly being caused by either the unit being oversized (my guess) or they aren't running it in dehumidifying mode or low speed fan setting (if that unit has such features) while operating in humid conditions.   

Our Houghton rapidly dehumidifies (and cools) the cabin whether or not the fan is on high or low, as long as the compressor is running (AC or "dry" mode).  Water literally pours off the roof for the first 30 minutes.  The problem with humidity coming back up is definitely related to the compressor not running while the fan is running - which of course would happen more often if the unit is oversized and cycling (normal operation by the way).  It's been a bit of a learning curve, but no way I'd ever go back to the Dometic or something that loud.  We are still super happy with the Houghton over the original Dometic.

[CRM]

2 hours ago, NCeagle said:

Our Houghton rapidly dehumidifies (and cools) the cabin whether or not the fan is on high or low, as long as the compressor is running (AC or "dry" mode).  Water literally pours off the roof for the first 30 minutes.  The problem with humidity coming back up is definitely related to the compressor not running while the fan is running - which of course would happen more often if the unit is oversized and cycling (normal operation by the way).  It's been a bit of a learning curve, but no way I'd ever go back to the Dometic or something that loud.  We are still super happy with the Houghton over the original Dometic.

That Houghton designs their units to run the fan continuously after the compressor shuts down is a head scratcher for sure and definitely can contribute to your humidity problem, but based on your description of how quickly it cools down your cabin, even on low fan, I would bet that your unit is also oversized for the conditions you use it in. Oversized units usually don't pose much of a problem until high humidity enters the picture, at which point they do such a good job at removing sensible heat (thermostat setting) that they don't run for a long enough time to reduce the humidity to comfortable levels. At that point you have two options, run it cooler inside than you desire so it runs longer and hopefully reduces the humidity level to your liking, or use a dehumidifier and let it duke it out with your AC unit. I say duke it out since it's also heating the air in the cabin as it reduces humidity.

Another side effect of running an oversized unit is that even if you do knock the humidity in the air down quickly after starting up you may still have a higher amount of moisture remaining in your cushions, blankets, clothes, etc that will release into the lower humidity cabin air after your unit shuts down. Combine this with the blower continuing to run over the wet evaporator coil and the humidity from breathing and the cabin humidity can climb fast without much or any change in actual temperature.

 

 

 

[GarryandKristi]

On 10/6/2022 at 2:18 PM, CRM said:

Their humidity problem is undoubtedly being caused by either the unit being oversized (my guess) or they aren't running it in dehumidifying mode or low speed fan setting (if that unit has such features) while operating in humid conditions.   

I agree with your thoughts.  Short cycling is the most likely problem. We get this in our dometic penguin that came with the elite II in 2018.  Air conditioners are by nature dehumidifiers (they why they have condensate lines). Having to run a dehumidifier seems like poor design when you have AC so it must be a sizing and/or fan speed issue.  We’ve lived in the south for many years and never have had issues with humidity in our house even with outside dew points in the upper 70s. And that is even with a whole house ventilation system with some outside air being pulled in. Of course house hvac systems are far better than rv systems in design, etc. 

[SeaDawg]

I think another part of the equation is that rv ac systems are probably designed for the typical drafty, uninsulated stick-built  trailers and motor homes. They're almost expected to run more or less continuously in high heat and humidity. 

At least the Houghton is quiet. I think it's set up to run on a 2 degree differential, like most,, and I've not found a way to change it. 

@CRM, point well taken on the humidity absorbed by textiles, etc. At least the Oliver walls and furniture,  other than cushions, can be wiped down and don't absorb excess humidity.  During the evening and night, though, we all tend to add humidity. Showers, cooking, and breathing add a bunch, even when we run exhaust fans. 

Since I can't hold my breath all night, I'll live with it.  😅 (pun intended)

I'll look forward to reports in the Truma. 

Home ac systems are designed for a single climate zone. Rv systems have to be a compromise...

[NCeagle]

13 hours ago, GarryandKristi said:

We’ve lived in the south for many years and never have had issues with humidity in our house even with outside dew points in the upper 70s. And that is even with a whole house ventilation system with some outside air being pulled in.

Same here for the main floor in our house (in NC also).  The HVAC system keeps the humidity between 45-55% even when the dew points are in the 70s because the AC runs a lot and therefore keeps the moisture at bay.  However, we do have to run a dehumidifier along with our HVAC in our basement, as do others I know that have a basement anywhere in the US (basement is cooler and the AC doesn't run enough).  As I mentioned in a post above, if you truly want to control BOTH humidity and temperature, then you need both as they are designed for different purposes.  There are many articles and research out on the web that state the same.  

[CRM]

4 hours ago, NCeagle said:

 As I mentioned in a post above, if you truly want to control BOTH humidity and temperature, then you need both as they are designed for different purposes.  There are many articles and research out on the web that state the same.  

While there are situations like a cold damp basement where only a dehumidifier will work to remove excessive moisture, that's not what's happening in the video from the original post. Their issue is undoubtedly due to short cycling of an oversized unit. They have a 13.5k unit in a 10 1/2 long insulated truck camper which will never run long enough under the conditions they're in to keep humidity in check.

Eventually, VRF (variable refrigerant flow) systems like those used in residential mini splits will be available for RV's and will virtually eliminate these humidity issues. There are currently wall mounted units available that are rated for 13k that have the ability to throttle down to 2.5k automatically based on temp/humidity settings. 

 

[Mike and Carol]

What size Houghton are folks using in their Olivers?

[Hokieman]

28 minutes ago, Mike and Carol said:

What size Houghton are folks using in their Olivers?

Mike…I made some notes for myself as this is on my future mods list.   RecPro Houghton 13.5 is quieter, uses less power, and has a heat strip.   Moves as much air on Low as 9.5 moves on Medium or High.  More practical than 9.5 BTU in Elite 2 size.

Got Earplugs?

[Geronimo John]

On 10/5/2022 at 4:11 PM, GarryandKristi said:

I suspect the issue is running the fan constantly versus on auto so unconditioned air is being pulled in.

Exactly.  

On 10/7/2022 at 1:57 AM, CRM said:

At that point you have two options, run it cooler inside than you desire so it runs longer and hopefully reduces the humidity level to your liking, or use a dehumidifier and let it duke it out with your AC unit. I say duke it out since it's also heating the air in the cabin as it reduces humidity.

For some on shore power or large generator, maybe, but wasteful.   But for boon-dockers using small generators (2000 to 2200 Honda's for example), that solution likely just does not work out so well.   

Does anyone know if the fan is a multi speed motor or a speed control motor?

If multi speed, say three speed (Hi, Medium, Low) then why not add a fan speed selector switch with the same number of speeds.  Then power the fan speed selector switch input from the compressor power feed.  Circulation fan would run only when t-stat is calling and the compressor relay is energized.  Fan would run at the speed that was set on the selector switch.  When the t-stat reaches it's set temperature, the unit control board will shut down both the compressor and fan.  Humidity problem greatly reduced.

Seems to me that this could be a simple mod.  Any chance Houghton could comment on this?  Your thoughts?

GJ

[CnC]

On 10/6/2022 at 7:16 AM, CRM said:

I think a big part of the humidity issues some are having is that most units are oversized for the volume of airspace being conditioned

Correct!  When temperatures are satisfied too quickly, the compressor ceases removing humidity.

Charlie

[CRM]

1 hour ago, CnC said:

Correct!  When temperatures are satisfied too quickly, the compressor ceases removing humidity.

Charlie

I, and others, tried explaining to the woman in the video that her problem was due to an oversized unit, but she won't even consider it because the people who sold it to her said it was sized correctly.

[Geronimo John]

On 10/7/2022 at 1:57 AM, CRM said:

That Houghton designs their units to run the fan continuously after the compressor shuts down is a head scratcher for sure

Certainly an odd design.  I know that on some A/C systems it is normal to run the fan after compressor shut down for a short time to lower the head pressure.  Sort of like an unloader in a shop air compressor.  The intent for those set-ups is to decrease the re-start torque.  But to run it continuously after compressor shut down boggles my mind as well.  

[Geronimo John]

On 10/5/2022 at 11:49 PM, NCeagle said:

but if it' s mixing in outside air that may be something that could be improved with the design

I do not believe that it mixes outside air with conditioned air as there is no interconnection between the two. 

If there was, you would have to insect screen and filter the OA intake.  The unit only has one filter, and it is for cleaning the return air going into the unit from the cabin.

Also, such a design could lead to a really bad insect migration into the cabin problem.   Can you imagine a Florida swamp no-see-un's swarming around such an air intake?  Sends shivers down my back...

I strongly believe the cause is re-evaporation of condensate on the evap coil by the continuously running supply air fan. 

GJ 

[Hokieman]

On 12/10/2022 at 1:20 PM, Hokieman said:

Mike…I made some notes for myself as this is on my future mods list.   RecPro Houghton 13.5 is quieter, uses less power, and has a heat strip.   Moves as much air on Low as 9.5 moves on Medium or High.  More practical than 9.5 BTU in Elite 2 size.

Got Earplugs?

Correction:  ThecRecPro Houghton 13.5 is a heat pump, does not have a heat strip.  I re-read the lengthy thread “Got Earplugs” and there was some confusion and mis-reporting over heat pump vs. heat strip.   The heat pump function is a significant benefit over the Dometic Penguin II, will save a lot of propane when on shore power.